Papers by Keyword: Open Circuit Voltage Decay

Abstract: Among all the material parameters of a semiconductor, the lifetime of the carriers is one of the most complex, as it is a function of the dominant recombination mechanism, the number of carriers, the structural parameters and the temperature. Nevertheless, the lifetime of the carriers is a very useful and fundamental parameter to be determined for the qualification of the semiconductor in order to allow the improvement of the manufacturing process and the optimization of the operation of the semiconductor device. Thus being strongly linked to many physical and electronic parameters, the lifetime of the carriers cannot be provided only with a theoretical average value and an experimental measured value must be obtained. In the case of semiconductor junctions, precise measurements of the open-circuit voltage decay, OCVD, make it possible to trace the lifetime of the carriers through the device. An automated method for OCVD measurements presented in this contribution overcomes the main limitations that arise in the standard method when used for the characterization of the lifetime of carriers as it achieves the "open circuit conditions" of the device under test and reduces inherent noise of the differential operation mode of the method.

Abstract: Compact simulation models of two key silicon carbide power components, the Junction Barrier Schottky diode and the power MOSFET, which are taking into account the effect of irradiation by highenergy electrons, were developed. Two 1.7 kV class devices: the 14 A JBS diode C3D10170H and the 5 A SiC power MOSFETs C2M1000170D produced by Wolfspeed were irradiated by 4.5 MeV electrons in the dose range up to 2000 kGy. Electrical characteristics were measured prior to and after irradiation. Radiation defects were studied by deep level transient spectroscopy and the effect of irradiation on device characteristics was established. SPICE models taking into account the irradiation fluence were proposed and calibrated using the parameters extracted from experiment. Simulated characteristics show a very good agreement with reality.

Abstract: The effect of local lifetime control by proton irradiation on the OCVD response of a 10 kV SiC PiN diode was investigated. Carrier lifetime was reduced locally by irradiation with 800 keV protons at fluences up to 1x10¹¹ cm^-2. Radiation defects were characterized by DLTS and C-V profiling; excess carrier dynamics were measured by the OCVD and analyzed using the calibrated device simulator ATLAS from Silvaco, Inc. Results show that proton implantation followed by low temperature annealing can be used for controllable local lifetime reduction in SiC devices. The dominant recombination centre is the Z_1/2 defect, whose distribution can be set by irradiation energy and fluence. The local lifetime reduction, which improves diode recovery, can be monitored by OCVD response and simulated using the SRH model accounting for the Z_1/2 defect.

Abstract: This paper reports on the influence of temperature on the electrical carrier lifetime of a 3.3 kV 4H-SiC PiN diode processed with a new generation of SiC material. The Open Circuit Voltage Decay (OCVD) is used to evaluate ambipolar lifetime evolution versus temperature. The paper presents a description of the setup, electrical measurements and extraction fittings. The ambipolar lifetime is found to rise from 600 ns at 30 °C to 3.5 μs at 150 °C.

Abstract: Minority carrier (hole) lifetime investigations are conducted on identical 6H-SiC p+-n structures by electrical (reverse recovery, open circuit voltage decay) and optical (time-resolved photoluminescence) techniques. The p+-n diodes are fabricated by Al implantation. Depending on the particular analysis technique, the lifetime is determined either electrically in different regions of the p+-n diode or optically in the n-type 6H-SiC epilayer and results, therefore, in different values ranging from ≈10 ns to 2.5 µs.